146 BRITISH AND EUROPEAN FOSSIL ELEPHANTS. 



proportion to the increase in the width of the crowns. But 

 these compressed ridges are still the homologues of the 

 massive divisions seen in the crowns of the molars of the 

 Mastodon, and, as such, it is but correct to retain the same 

 name for them. The obvious manner in which their elonga- 

 tion and compression affect the aspect of the crown is 

 embodied in the term ' coronis lamellosa,' and the difference 

 of degree by the terms ' broad-' and ' narrow-ridged,' instead 

 of ' thick-' and ' thin-plated ' molars. 



The mammillary divisions of the ridges in the Mastodons, 

 when worn, form discs, i.e. a depressed surface of ivory, 

 surrounded by a raised rim of enamel ; and by the further 

 progress of wear the separate discs become confluent into 

 larger discs, that are either transverse or trefoil-shaped and 

 alternate. In Euelephas the divisions of the compressed 

 ridges form finger- or quill-shaped processes, which at first 

 are ground down into distinct ' annular discs ' ; two or three 

 of these then become confluent into a compound oval disc ; 

 and at length the separate oval discs run together, forming 

 a transverse band (' ruban ' of Cuvier). Although it may not 

 be strictly logical to apply the term ' transverse discs ' to 

 these narrow bands (tsenise sernidetritse), still they may be 

 regarded as very flattened ellipses ; and I have found it con- 

 venient to use the term in this arbitrary sense in order to 

 maintain a uniformity of terms in designating the same object 

 under different modifications. 



The enamel-plates furnish the most important distinctions. 

 1st. In regard of the thickness : in E. primigenius they are 

 only half as thick as in E. meridionalis, and thinner than in 

 the Indian Elephant or in E. (Euelephas) antiguus. 2nd. 

 Surface-characters. The inner surface, where in contact with 

 the ivory, is usually smooth ; and the edges of the plates, in 

 the worn discs, are even, whether the plates are straight or 

 plaited. The outer surface is rugous and uneven in two 

 directions : — first, vertically, from parallel or divided ribs se- 

 parated by anastomosing channels, which are close-set and 

 irregular in size, and which are most marked below, disap- 

 pearing upon the apices of the digitations ; and secondly, trans- 

 versely, from parallel, wavy, contiguous, and very frequent 

 rugce or superficial puckering. In the vertical section these 

 communicate a ragged, feathered edge to the outer surface 

 of the plates ; while the transverse section of the ribs and 

 channels, in the worn plates, produces a spurious appearance 

 of crimping, which it is important to distinguish from 

 plaiting or folding of the enamel upon itself. The undulated 

 margins caused by these alternate ribs and channels multiply 

 the triturating inequalities of the enamel, and they serve 







